Peaceful protesters rally in Brisbane at G20 talks

Up to 1,000 people staged peaceful protests outside the G20 summit in Brisbane Saturday, braving oppressive heat and a heavy police presence to bring attention to their causes.

They rallied in a city in security lockdown as it hosts the two-day talks between the high-profile leaders, including US President Barack Obama, China's Xi Jinping and Russia's Vladimir Putin.

"They say warfare, we say welfare," shouted some as they were watched by scores of police, while others carried banners against poverty and inequality as the temperatures soared past 30 degrees Celsius.

Demonstrations focused on a eclectic range of issues besides the G20 including climate change, global inequality and the conflict in Ukraine.

June Norman, 74, was rallying because she wanted climate change on the agenda at the G20, which Australia has attempted to focus narrowly on economic issues.

"I'm here to bring the attention the fact that the (Australian) prime minister has not brought climate change to the G20," she said.

"And we think it's a very serious issue that should have been spoken about all around the world, but definitely at the G20 when we have so many influential people here."

Another protest, in which people lay on the ground to symbolise the deaths of those onboard Malaysia Airlines Flight MH17 shot down over Ukraine in July, claimed Putin had blood on his hands and was not welcome in Australia.

"One of the great things about Australia is that people with all points of view get to make their views known in a democratic society but that's the kind of society Putin objects to," said Pete Shmigel from the Australian Federation of Ukrainian Organisations.

Another protester, Sean Cleary, said he was making a statement about the situation in Mexico, where 43 students are feared killed by a drug cartel acting in collusion with police.

Mexico's President Enrique Pena Nieto is expected to leave the summit after the first day of talks on Saturday as controversy about the suspected murders rages back home.

"What the hell is he doing here in Brisbane when he should be in Mexico fixing the problem?" Cleary said.

Police praised protesters for their conduct during the peaceful march through Brisbane to a park near the G20 leaders' summit venue.

Queensland state police, out in force and bolstered by colleagues from New Zealand and elsewhere in Australia, said only three arrests were made, one for trespass and two for carrying banned items.

They would not detail what the items were but media reports said they were gas masks.

The most unusual protest was in support of the G20, with a rally for free market capitalism which those taking part said had helped millions of Chinese escape poverty.